Deadly Arizona Flash Flood Created '40-Foot Wide Black Wave'

A flash flood swept through central Arizona on Saturday, killing at least nine people who had gathered at a popular swimming hole for a birthday celebration. The family was relaxing alongside a mountain stream in Tonto National Forest, unaware that summer thunderstorms had just dropped heavy rains upstream. Floodwaters six feet high suddenly swept through the canyon, according to the AP. Video shows fast-moving waters rushing through a canyon as people cling to trees. First responders called it a "40-foot-wide black wave" moving at 45 miles per hour, The Arizona Republic reports . "We had a strong thunderstorm with strong rains move through the area, which created a flash flood problem," said Sgt. David Hornung of the Gila County Sheriff's Office....